J. Benedito

Use of ultrasound to increase mass transport rates during osmotic dehydration

Experiments on osmotic dehydration of 1 cm apple cubes in 70 °Brix sucrose solution using ultrasound treatment were carried out at 40, 50, 60 and 70 °C. Acoustic pressure and frequency was measured to characterize the ultrasonic bath. Mass transfer was described by Ficks unsteady state diffusion equation. An important influence of the solution temperature on water transport was obtained. Measured water diffusivity coefficients (Dw) ranged from 2.6 × 1010−10 m2 s−1 at 40 °C to 6.8 × 10−10 m2 s−1 at 70 °C. Similar sucrose gain was measured at different temperatures, with an average effective sucrose diffusivity coefficient (Ds) (7.9 ± 0.2) × 10−11 m2 s−1. Similar experiments were performed under dynamic agitation conditions. A significant decrease in water and solute transport rates was detected when agitation was applied instead of sonication.

High intensity ultrasound effects on meat brining

Pork loin (longissimus dorsi) samples of two different geometries, cylinders and slabs, were immersed in saturated NaCl brine for 45min under different conditions: without brine agitation (STAT), with brine agitation (AG) and with ultrasound application (US) at eight levels of ultrasonic intensity. Moisture content change and NaCl gain were considered in order to evaluate the difference in the brining treatments. No significant differences were found in moisture and NaCl content of samples treated under STAT conditions and AG conditions, while the influence of ultrasound on the mass transfer process during meat brining depended on the intensity applied. There was an ultrasonic intensity threshold above which the influence of ultrasound appeared. At the highest level of intensity studied, the water content of samples was significantly higher than the initial water content of meat. As regards NaCl transfer, once above the intensity threshold, the increase in the NaCl content was proportional to the applied ultrasonic intensity. Not statistically significant differences were found for sample geometry.

Composition assessment of raw meat mixtures using ultrasonics.

The use of ultrasonic velocity measurements to determine the composition of dry fermented sausages was assessed. Mixtures of ground lean and fatty tissues were prepared to cover a wide range of fat (2-90 wt.%), moisture (7-76 wt.%), and protein (2-21 wt.%) contents. The ultrasonic velocity in fat decreased on average 5.6 ms(-1) per °C increase in temperature, due to the negative temperature coefficient for fat and the fat melting, which is observed in (DSC) differential scanning calorimetry analysis. The ultrasonic velocity temperature dependence allowed the determining of the fat, moisture and protein+others content, by measuring the ultrasonic velocity in the mixtures at 4 and 25°C and using a semi-empirical equation. The explained variance was 99.6% for fat, 98.7% for moisture and 85.4% for protein+others. The results obtained show the feasibility of using ultrasonic velocity measurement to assess the composition of meat products such as dry fermented sausages, rapidly and non-destructively.

Application of low intensity ultrasonics to cheese manufacturing processes

Ultrasound has been used to non-destructively assess the quality of many foods such as meat, fish, vegetables and dairy products. This paper addresses the applications of low intensity ultrasonics in the cheese manufacturing processes and highlights the areas where ultrasonics could be successfully implemented in the future. The decrease of ultrasonic attenuation during the renneting process can be used to determine the optimum cut time for cheese making. The ultrasonic velocity increases during maturation for those types of cheese that become harder during this manufacturing stage, thus being an indicator of the maturity degree. Moreover, ultrasonic measurements could be linked to sensory parameters. From the ultrasonic velocity measurements at two different temperatures, it is possible to assess cheese composition, thus allowing an improvement in the quality and uniformity of cheese commercialization. In addition, in pulse-echo mode it is possible to detect cracked pieces due to abnormal fermentations and also to assess the distance of the crack from the surface.

Ultrasonic determination of the composition of a meat-based product

Abstract The use of ultrasonics as an analytical technique to estimate the composition of a fermented meat-based product (sobrassada) was assessed. Moisture, fat and protein contents and ultrasonic velocity at 4, 8, 12 and 25 °C were measured in samples using different formulae. In this study, it was considered that a meat-based product is formed of three different constituents: fat, water and protein+others. Ultrasonic velocity was related, by a semiempirical equation, to the composition and the ultrasonic velocity of the above three components. The ultrasonic velocity temperature dependence allowed the determination of fat, moisture and protein+others contents. The explained variance was 98.0% for protein+others, 97.6% for fat and 95.6% for moisture. The results obtained show the feasibility of using ultrasonic velocity measurement to assess, in a rapid and non-destructively way, the composition of a meat-based product.

Use of ultrasound to assess Cheddar cheese characteristics.

Blocks of Cheddar cheese were matured in temperature-controlled chambers at 5 and 12 degrees C. The ultrasonic velocity increased during maturation ranging from 1657 to 1677 ms-1 at 12 degrees C and from 1684 to 1693 ms-1 at 5 degrees C. The ultrasonic velocity was related to the square root of the deformability modulus and the slope in puncture. The increase of velocity during maturation shows the feasibility of using an ultrasonic device to non-destructively monitor Cheddar cheese maturity. Ultrasound velocity was measured at different temperatures. The velocity decreased with increasing temperature, and from the slope of the first part of the temperature-velocity curves it was possible to non-destructively assess the moisture content of different types of cheese.

High-power ultrasonic system for the enhancement of mass transfer in supercritical CO2 extraction processes

Oil is an important component of almonds and other vegetable substrates that can show an influence on human health. In this work the development and validation of an innovative, robust, stable, reliable and efficient ultrasonic system at pilot scale to assist supercritical CO(2) extraction of oils from different substrates is presented. In the extraction procedure ultrasonic energy represents an efficient way of producing deep agitation enhancing mass transfer processes because of some mechanisms (radiation pressure, streaming, agitation, high amplitude vibrations, etc.). A previous work to this research pointed out the feasibility of integrating an ultrasonic field inside a supercritical extractor without losing a significant volume fraction. This pioneer method enabled to accelerate mass transfer and then, improving supercritical extraction times. To commercially develop the new procedure fulfilling industrial requirements, a new configuration device has been designed, implemented, tested and successfully validated for supercritical fluid extraction of oil from different vegetable substrates.

Quality assessment of Iberian pigs through backfat ultrasound characterization and fatty acid composition

Five batches of Iberian pig backfat of different breeds and with differing feeding regimes were analysed as to their fatty acid composition and textural, thermal and ultrasonic properties. The feeding regime affected the backfat composition more than the breed of the animals. The higher the oleic acid content in the feeding regime, the higher the monounsaturated fatty acid content in the samples. Ultrasonic velocities ranged from 1609 to 1631m/s. A change in the slope of the velocity versus temperature curve was found at 6°C, coincident with a change in the melting rate found in the differential scanning calorimetry. Discriminant analysis using ultrasonic measurements allowed 94.7% of the samples to be correctly classified in the batches considered, while the use of the fatty acids composition correctly classified 86.2% of the samples. Therefore, ultrasonic techniques could be useful in the characterization and classification of backfat samples from Iberian pigs.

The use of ultrasound velocity measurement to evaluate the textural properties of sobrassada from Mallorca

Abstract The usefulness of ultrasonic velocity measurements as a non-destructive technique to evaluate the moisture content and textural properties of sobrassada de Mallorca (a raw cured pork product) was assessed. Moisture content, ultrasonic velocity and textural properties were periodically measured in samples of sobrassada during ripening at 15°C and 75% RH. From the results obtained, two periods of ripening could be clearly distinguished, a first period (0–40 days of ripening) and a second period (40 to the end of the ripening), under the experimental conditions used in this study. The ultrasonic velocity could be mathematically related with the moisture content and textural parameters such as hardness, compression work, maximum puncture force and puncture work during the first period of ripening. In the second period, some physical modifications were inferred to occur which could be detected through the textural parameters, the ultrasonic velocity and by using optical microscopy. Overall, these results showed the ultrasonic techniques could be used to accurately estimate the moisture content and the textural parameters of sobrassada during the first period and also as a reliable method to detect changes in textural properties after prolonged ripening.

Review: Low intensity ultrasonics in food technology / Revisión: Ultrasonidos de baja intensidad en tecnología de alimentos

Ultrasonic applications can be classified into low intensity or high intensity applications. The latter are used to modify a process or product with ultrasonics, while in low intensity applications the process or product modifies the ultrasonic signal, thus providing information about the product. Low inten sity ultrasonics in food technology can be used to monitor a process (liquid level, flowmeters) or to determine the quality of food products. Since ultrasonic techniques are rapid, non-destructive, easy to automate and relatively inexpensive, the number of applications is rapidly growing in this field. Ultrasonics can also be considered for use in laboratory testing devices to determine physical and chemical properties of foods. Ultrasonics has been used to determine texture, composition and physical state in liquid and solid foods. The commonly measured ultrasonic parameters are velocity, attenua tion and frequency spectrum composition. Velocity is the parameter used most since it is the simplest and most reliable measurement. This paper reviews the basic principles of ultrasonics, the most suit able techniques for each type of application, the testing devices needed to make measurements and the most interesting applications.